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# Edexcel FP3 June 2015 - Official Thread watch

1. Can someone explain how they have found the normal to the plane in Qn 7a P6 JUNE 2003
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2. P6 - JUN03 - QP.pdf (54.1 KB, 106 views)
3. P6 - JUN03 - MS.pdf (156.3 KB, 986 views)
4. For d, I did AQ²=14+(2rt35)² . Then square rooted that. But that gives 4root21 instead of the answer which is supposedly root 154 . can someone help?

EDIT: did it - I did 14² instead of (root14 )²
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5. (Original post by Boop.)
Can someone explain how they have found the normal to the plane in Qn 7a P6 JUNE 2003
I'm pretty sure that there is a typo and on the exam paper it should be -i + 5j + 3k rather than -i + 2j + 3k
6. (Original post by Boop.)
Can someone explain how they have found the normal to the plane in Qn 7a P6 JUNE 2003
I think the paper's got a typo. Where it states the equation of the line the 2j should be a 5j. Then you use that line's direction as the normal!
7. http://imgur.com/m3DlMGQ

Can someone explain 2c, if i was to lets lets say z = 3 i would get a different eigenvalue, but the mark scheme seems to say that i cannot do this.

Thanks
8. (Original post by physicsmaths)
Na didn't bang it one of my solutions had errors so I'm sitting in 70s which might not even get me a 1. My partials were **** aswell.

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Well still much better than a lot of people. Don't worry you'll still make your offer
9. (Original post by DanTheMan358)
Well still much better than a lot of people. Don't worry you'll still make your offer
Hope so. I'm in the high 50s/ low 60s in III, borderline in both . WBU what's your offer?

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10. (Original post by physicsmaths)
Hope so. I'm in the high 50s/ low 60s in III, borderline in both . WBU what's your offer?

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Got Warwick firmed, Step I weren't great and II was pretty much a disaster. So will likely end up at insurance . Should have put more effort into step but I wanted nice A levels lol.
11. can some one explain how that get (1 + x^2 ) on the NB line

http://imgur.com/FMCaUYQ
12. What are the formulas for surface area/volume by revolution around the y axis?

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13. (Original post by DanTheMan358)
Got Warwick firmed, Step I weren't great and II was pretty much a disaster. So will likely end up at insurance . Should have put more effort into step but I wanted nice A levels lol.
I was opposite put all my time into step and flopped physics, maths and fm are chilled though.

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14. (Original post by BP_Tranquility)
What are the formulas for surface area/volume by revolution around the y axis?

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They're in the formula booklet; volume of revolution is in C4 though.
15. (Original post by ninjasinpjs)
can some one explain how that get (1 + x^2 ) on the NB line

http://imgur.com/FMCaUYQ
They multiplied the numerator and denominator by (1 + x^2)^(1/2)
16. (Original post by 13 1 20 8 42)
They multiplied the numerator and denominator by (1 + x^2)^(1/2)
i know they done that but when i get the dy/dx expression and multiply out the two fractions i get the denominator as 1 where is should be (1 + x^2 ), it would be really helpful if you could show me how they got that.
17. (Original post by 13 1 20 8 42)
They're in the formula booklet; volume of revolution is in C4 though.
The ones in the booklet are for rotation around the x axis, what about around the y axis?

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18. (Original post by ninjasinpjs)
i know they done that but when i get the dy/dx expression and multiply out the two fractions i get the denominator as 1 where is should be (1 + x^2 ), it would be really helpful if you could show me how they got that.
You should get that. The NB line is only dealing with the second fraction. If you simplify the expression you have you will obtain the necessary dy/dx.
That NB line just draws attention to another way someone may have approached the question, by first simplifying the second fraction.
19. Do we need to know about hyperbolae and ellipses with foci on the y axis?

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20. (Original post by BP_Tranquility)
The ones in the booklet are for rotation around the x axis, what about around the y axis?

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Well I don't know if they can ask that. For volume they specifically say that it won't be rotated about the y-axis but they admittedly don't say that about surfaces and arc length. Nevertheless they would be exactly the same except you would swap all the x and y values around and use the upper and lower y values rather than upper and low x values; so (dx/dy) instead of dy/dx, of course integrate with respect to y, 2xpi instead of 2ypi and so on. The parametric variants wouldn't change.

Edit: there is one difference with surface area mentioned in the textbook; you can (also, the other formula still works) find the surface area for rotation about the y-axis by simply swapping out y for x in the (2piy) bit and leaving everything else the same.
21. (Original post by 13 1 20 8 42)
You should get that. The NB line is only dealing with the second fraction. If you simplify the expression you have you will obtain the necessary dy/dx.
That NB line just draws attention to another way someone may have approached the question, by first simplifying the second fraction.
alright, ill use my denominator of 1 to simplify to the answer, thanks

22. Could anyone explain how to do this question (part c)? I got 3.74 but the mark scheme says 3.61?

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